With the renewed interest in Stirling engines there has been ever increasing attempts to improve engine efficiency and reduce cost so as to produce a cost effective product. One of the means of improvements in this regard includes variations in the design of the piston and cylinder head as for example can be seen in U.S. Pat. Nos. 4,271,669 issued June 9, 1981; 3,899,888 issued Aug. 19, 1975; and 3,636,719 issued Jan. 25 1972. These representative engines are an attempt to maximize the isothermal change in condition and thereby improve the degree of thermal efficiency of the engine. However, while such arrangements may be more efficient than prior devices, the designs are relatively complicated, difficult to manufacture, expensive or subject to other disadvantages such as excessive dead volume. This inhibits the engine cycle performance, limiting their application.
Accordingly, current Stirling production engines usually utilize a separate heater or cooler volume in addition to the main expansion volume. This practice has the disadvantage of increasing the overall volume resulting in relatively unproductive (thermodynamically) working gas volume and requiring alternative multiple parts which increase the failure probabilities and raise costs.
In my copending application entitled "Integral Finned Heater/Cylinder Head for Stirling Engines" filed concurrently herewith, under Ser. No. 423,526, and incorporated by reference, there is disclosed a cylinder head and piston which are formed into an interlocking relationship via a conical finned piston and correspondingly finned internal surface of the cylinder head at the hot end of the cylinder. The piston is hollow having a regenerator therein through which a working gas can pass eliminating a portion of the excess working volume attributable to a separate regenerator.
The present invention is directed towards further improving on this concept.